Thymus-induced recovery of age-related decrease of brain cortex α-and β-Adrenoceptors

It has previously been demonstrated that thymus exerts a regulatory influence on β-adrenergic system during aging. In particular, it has been shown that thymus can correct the β-adrenoceptor density decrease in old mice. In the present paper results of experiments are reported dealing with the influence of the thymus on α-adrenoceptors of mouse brain cortex. Both subtypes of α-adrenoceptors are studied separately, using different labelled ligands. Results show that αI-adrenoceptor density decreases in old animals, while α2-adrenoceptor density does not change significantly. A neonatal thymus grafted into old recipients is capable of correcting the alteration observed in old mice. The differential impairment of α-adrenoceptors resembles that one previously observed on β-adrenoceptors, where β1-type decreases in number during aging with a parallel decrease of adenylyl-cyclase activity, while β2-type remains unchanged.